Future public telecommunications networks are likely to be based on optical fiber transport and are expected to support a heterogeneous mix of broadband services. In order to enable design flexibility for these networks, statistical packet switching techniques will probably be used to achieve uniform switching and multiplexing of multiple bit rate data streams. An example of such a statistical packet switching technique is Dynamic Time Division Multiplexing (see, e.g. "Dynamic Time Division Multiplexing," U.S. patent application Ser. No. 118,977 filed on Nov. 10, 1987 for H. J. Chao, S. H. Lee, and L. T. Wu and assigned to the assignee hereof.)
A key element in such a packet network is a large capacity, broadband self-routing packet switch. A self-routing packet switch typically comprises a Batcherbanyan network implemented in CMOS using VSLI (see, e.g. Batcher-banyan Packet Switch With Output Conflict Resolution Scheme, U.S. patent application Ser. No. 919,793 filed on Oct. 16, 1986 for E. Arthurs and Y-NJ Hui and assigned to the assignee hereof), now U.S. Pat. No. 4,817,984, issued Mar. 28, 1989. The Batcher-banyan based switch, like other existing electronic switches, requires the demultiplexing of incoming multigigabit optical transmission channels into sub-rate channels. These lower rate data streams are switched and then remultiplexed up to the multigigabit optical transmission rate after the switch.
It is an object of the present invention to provide a packet switch which, in contrast to the above-described electronic switches, utilizes optical components and devices to implement switching functions.
It is a further object of our invention to provide a packet switch in which both internal and external collisions of packets are prevented.